Ran the beta installer and then Setup.exe aborted with the above message
1263.logos4setup.log
I was running in a standard user account and elevation was requested. I have latest 4.5a installed in my Admin account.
UPDATE:
I found a .NET 3.5 Windows update I hadn't installed. When I logged on again Setup resumed and downloaded & installed Prerequisites. Then nothing - no download, no messages.
5633.PrerequisitesInstall.zip
SUCCESS:
Manually ran Setup.exe from its download location and Logos4 was downloaded and installed. It would appear that more testing of this Update script is needed.